thread_win32.c (rb_w32_wait_events_blocking): use
ruby_thread_from_native() instead of GET_THREAD() because
GET_THREAD() doesn't always return the current thread and
WaitForMultipleObjects() at rb_w32_read() doesn't return by
Thread#kill. This fixes TestQueue#test_thr_kill failure on
Windows.

thread_win32.c (rb_w32_wait_events): use ruby_thread_from_native()
instead of GET_THREAD() for consistency with the above change.

thread_win32.c (rb_w32_wait_events_blocking): use
ruby_thread_from_native() instead of GET_THREAD() because
GET_THREAD() doesn't always return the current thread and
WaitForMultipleObjects() at rb_w32_read() doesn't return by
Thread#kill. This fixes TestQueue#test_thr_kill failure on
Windows.

thread_win32.c (rb_w32_wait_events): use ruby_thread_from_native()
instead of GET_THREAD() for consistency with the above change.